Microsoft Windows

Microsoft Windows is a range of commercial operating environments for personal computers. The range was first introduced by Microsoft in 1985 and eventually came to dominate the world personal computer market. All recent versions of Windows are fully-fledged operating systems.

16-bit Operating environments. Although they are often thought of as just graphical user interfaces or desktops, mostly because they use MS-DOS for filesystem services, 16-bit Windows versions already have their own executable file format and provide their own device drivers (graphics, printer, mouse, keyboard and sound). Most important, from the beginning they allow the user to (non-preemptively) multi-task graphical applications, something which competitors like GEM do not offer. Finally, they implement an elaborated segment-based software virtual memory scheme, which allows to run applications larger than available memory: code segments and resources are swapped in and thrown away when useless or memory becomes scarce and data segments move in memory when a given application has relinquished processor control. Examples include Windows 1.0 (1985) and Windows 2.0 (1987) and its close relative Windows/286.

Hybrid 16/32-bit operating environments. Windows/386 introduced a 32-bit protected modekernel and virtual machine monitor. For the duration of a Windows session, it provided a device virtualization for the disk controller, video card, keyboard, mouse, timer and interrupt controller. The user-visible consequence was that it became possible to preemptively multitask multiple MS-DOS environments in separate windows (graphical applications required switching the window to full screen mode). Windows applications were still multi-tasked cooperatively inside one of such real-mode environments. Windows 3.0 (1990) and Windows 3.1 (1992) perfected the design, notably thanks to virtual memory and loadable virtual device drivers (VxDs) which allowed them to share arbitrary devices between multitasked DOS windows. Most important, Windows applications could now run in 16-bit protected mode (when Windows was running in Standard or 386 Enhanced Mode), which gave them access to several megabytes of memory and removed the obligation to participate in the software virtual memory scheme. They still ran inside the same address space, where the segmented memory provided a degree of protection, and multi-tasked cooperatively. For Windows 3.0 Microsoft also rewrote critical operations from C into assembler, making this release faster and less memory-hungry than its predecessors.

Hybrid 16/32-bit operating system. With the introduction of 32-Bit File Access in Windows for Workgroups 3.11, Windows could finally stop relying on DOS for file management. Leveraging this, Windows 95 introduced Long File Names, reducing the 8.3 DOS to the role of a boot loader. MS-DOS was now bundled with Windows; this notably allowed to make it (partially) aware of long file names when its utilities where run from within Windows, but angered the competition. The most important novelty was however the possibility of running 32-bit multi-threaded preemptively multitasked graphical programs. Windows 95 had three versions (first one in 1995, subsequent bug-fix versions in 1996 and 1997; they notably added support for FAT32) and two versions of Windows 98 (1998 and 1999, named "Windows 98 Second Edition"). In 2000, Microsoft released Windows ME, which used the same core as Windows 98 but adopted the visual appearance of Windows 2000.

Fully 32-bit operating systems originally designed and marketed for higher-reliability business use with no DOS heritage. Examples include Windows NT 3.1 (1993, numbered "3.1" to match the Windows version), NT 3.51, NT 4.0, Windows 2000, Windows XP, and Windows Server 2003. Windows CE, for embedded systems, is also a true 32-bit operating system.

Windows XP introduced a new visual style dubbed "Luna", which updated the classic Windows style (a plain 2D look) with a more graphical appearance. The new style features bold colors and a larger titlebar and start button, leading many to call it the "playskool" interface (after a popular brand of children's toys). Users can still elect to use the old Windows 95/2000 visual style.

Modern operating systems need to cater for the vastly increased user base with a lower average computer skill level and the increased power and complexity of modern computer systems. Therefore, some technically savvy users accuse the Windows interface of isolating the user from too much of the inner workings of the computer, making it more difficult to control and configure some system features. However, this has always been an issue to some extent with GUI operating systems, and, to a lesser extent, almost all operating systems, by definition.

Microsoft publicly admitted their ongoing security problems shortly after the turn of the century and (according to their press statements) now regard security as the number one priority.

Microsoft releases security patches through its Windows Update service approximately once a month, although critical updates are made available at shorter intervals. In Windows 2000 and Windows XP, updates can be automatically downloaded and installed if the user elects to do so.

Microsoft introduced a new security initiative called Palladium in 2001. The system has since been renamed "Next Generation Secure Computing Base". Palladium is a system intended to allow a program to verify that it is unmodified, and is running on "trusted" hardware with "trusted" drivers and a "trusted" architecture. This, in theory, assures the software that it is running on unmodified software and hardware. Palladium has a particular use in DRM systems. A side effect of this, and some think the main reason for Palladium, is to lock out other operating systems at the hardware level; in particular, Microsoft's greatest threat, Linux. Microsoft may implement Palladium in later versions of Windows.

Microsoft has a number of new initiatives planned or in progress: .NET, Palladium and the "Longhorn" operating system, which is due in or around 2005, although some Microsoft executives have indicated that a 2006 release is likely. There is some current speculation that Microsoft may use .NET and Longhorn as a way of moving away from the Windows brand. It is suggested that this may help Microsoft avoid the consequences of antitrust actions, as it will be able to claim that the Windows successor is an entirely new product, and not subject to any regulation applied to Windows. Further down the road, there is the "Blackcomb" operating system, which is due sometime around 2008, and will have both a client (for the average user) and server version.

Windows NT 4.0 (released 1996) - the last version which ran on RISC architectures like DEC Alpha, MIPS and PowerPC. Later versions concentrated on x86-based hardware and - mainly as server OSs - the IA-64 line of CPUs.